This K01 application is designed to provide specialized training in research skills that will be used to improve the diagnostic assessment of alcohol tolerance, impaired control over drinking, and negative consequences in teens, and to develop and test an adolescent-specific definition of the alcohol abuse diagnosis. Three primary areas of career development will be addressed through courses, readings, tutorials and collaboration with local and national experts in applying skills directly to the proposed research. The first area is training in measures development and evaluation, and study of biologic, environmental, and individual difference influences on tolerance and impaired control over alcohol use. The second area is advanced study of principles and methods of developmental psychopathology and developmental issues in psychiatric nosology. The third area is training in longitudinal data analytic methods. These career development activities are highly integrated with the proposed research, which will be conducted within the NIAAA- funded Pittsburgh Adolescent Alcohol Research Center using 200 males and females age 14-18 recruited from addiction treatment programs and community sources. In-depth assessment of initial sensitivity to alcohol, tolerance to multiple alcohol effects, motivations and plans regarding alcohol use, and a range of psychosocial consequences will be used to improve validity in the measurement of alcohol problems among adolescents. Revised diagnostic assessment of tolerance that requires a 100% increase in consumption is predicted to show better concurrent and predictive validity compared to DSM-IV's 50% definition. Revised diagnostic assessment of impaired control that includes evaluation of motivations and plans for use will show better concurrent and predictive validity compared to DSM-IV impaired control criteria. An alternative definition of alcohol abuse defined by heavy drinking and recurrent alcohol-related negative consequences is predicted to better discriminate problem and non-problem drinkers compared to DSM-IV alcohol abuse. Results will improve the validity of alcohol diagnoses among adolescents, and will increase knowledge of the roles that tolerance and impaired control play in the onset and development of alcohol problems. This award will provide a solid foundation for the applicant to become an independent investigator specializing in adolescent alcohol problems.